Add a driver for the NS2009 resistive touchscreen controller chip by
Nsiway, which is connected via I2C.
Only polling is support now, as the hardware available now didn't use
the IRQ pin.
Pressure measurement is also not supported, as it will need more
investigation to convert raw readout to real value. Currently the
pressure readout is only used to detect pen up/down status.
Signed-off-by: Icenowy Zheng <icenowy@aosc.xyz>
Icenowy Zheng
0dbacea832